2 Answers
2

Looking at the list, take out your pencils and emphatically draw some arrows, free-hand circles, and other official-looking doodles as we work our way through a brief history of Stack Overflow.(this would be so much more entertaining as an animated video)

Stack Overflow is always written "Stack Overflow" (two words, capital letters) - Cross off all entries not written as such.

stack overflow trilogy

Stackoverflow trilogy

StackOverflow trilogy

SOFU would suggest that the Trilogy names form an initialism, which they do not. SOFU is based on all the Trilogy sites starting with the letter "S" followed by either "O", "F", or "U". Software heads recognized this as a regular expression which would be properly written S[OFU].

SOFU

The term "trilogy" refers to the original three sites in the series. Super User became the fourth site of the "trilogy in four parts," in the tradition of the five books of the Hitchhiker's Trilogy. So "The Trilogy" is a name affectionately applied to the group of sites, making it a proper noun--capitalized.

Stack Overflow trilogy

Stack Overflow trilogy sites

SO trilogy

trilogy

Stack Overflow is not nearly ubiquitous enough to usurp the exclusive use of a noun as a pronoun or a deity. One would not refer to "New Coke" as simply "New." The term must be applied in context to take on its full meaning.

Trilogy

Trilogy Sites

Trilogy sites

trilogy sites

trilogy websites

About "SO Trilogy": this is wrong but I'm getting tried of writing so let's just cross that off and hope nobody bothered reading this far.

SO Trilogy

The most official looking label is The Stack Overflow Trilogy. And by "official," I mean Really Cool Looking. Unfortunately in legal circles, use of the () symbol means—I appologise in advance for subjecting you to very technical Lawyer Talk—everyone can write "The Stack Overflow Trilogy" except Stack Overflow, Inc.

That leaves us with the proper phrasing: The Stack Overflow Trilogy.

Is it official? Yes, at least in the sense that if you told me "You are totally making this up," you would be correct. But the the little ♦ thing next to my name makes it at least appear authoritative (at least until ♦♦ comes along and says otherwise).

The OP asks about SO, SF and SU by name. But he's also asking about "all" the sites, and there are more now. I suppose you could still use The Stack Overflow Trilogy, but it's kinda ambiguous now. Are you referring to SO/SF/MSO? SO/SF/SU? SO/SF/SU/MSO? The entire network?

We've moved on. We're in the Stack Exchange era now. The SE 2.0 era, at that. Most of Robert's rules — heh heh — still apply; it would still be wrong to ignore basic grammar and write "stackexchange." So it seems to me that the answer should now actually be: